The present invention relates to thromboembolic protection, and more particularly relates to an instrument including a collapsible filter mounted on a tube such as a guidewire for thromboembolic protection.
It is common practice today to open occluded (i.e., blocked) or stenotic (i.e., narrowed) blood vessels by inserting a guidewire and then a catheter carrying a balloon shaped distal end, and inflating the balloon, which exerts radial force, to press the stenosis outward against the wall of the vessel. This procedure is called balloon angioplasty. Frequently, an implantable metallic stent will be used additionally to provide greater radial strength and longer-term patency. The stent can be delivered with a balloon catheter or on a special sheath. This procedure is called A stent placement.
During balloon angioplasty and stent placement of the stenotic lesion, there is the risk of dislodging fragments of plaque, thrombus (blood clots) or other material. If the lesion involves arterial circulation, then the particles could flow into smaller vessels in the brain, other organs or extremities resulting in disastrous complications. Likewise, if the lesions involve the venous circulation, then the thromboemboli could flow into the heart and lung possibly resulting in the demise of the patient.
There have been various devices and equipment to deal with stenotic lesions. As described, angioplasty and stents have been used to radially expand the lesion into the wall of the vessel. But these instruments can accidentally dislodge plaque and thrombus. Atherectomy devices are used to cut the plaque but have poor clinical results in actually treating the lesion and do not effectively trap thromboemboli.
Various patents have recently addressed th e subject with the use of balloons or straining devices. However, such designs do not effectively trap particles or are too traumatic in crossing high grade stenoses. The present invention provides these capabilities, in addition to providing a guidewire which can be used to deliver catheters and stents to treat the lesion.
This invention relates to an apparatus and method for collecting blood clots, pieces of plaque and other material that may be accidentally dislodged during interventional procedures in the human vasculature, such as arterial and venous angioplasty and stent placement. The apparatus includes a collapsible filter, which allows the dislodged fragments and thromboemboli to be captured and removed from the body. The filter is porous in order to allow red blood cells and other normal blood products to pass while the filter is open.
In one embodiment of the invention, the apparatus also serves a dual purpose as a guidewire. Once the distal end of the apparatus is advanced past the stenosis or targeted narrowing of the vessel, the operator may use the apparatus to advance various coaxial catheters and devices into position to treat the lesion. Balloon catheters, stent delivery systems, intravascular ultrasound catheters and other interventional systems can be advanced over the present apparatus.
An aspect of the present invention is to provide such a filter device carried by a tube such as a guidewire which is inserted into the occluded or stenotic vessel in a retracted position, and can be easily and remotely opened allowing effective trapping of thromboembolic material.
Another aspect of the invention is to provide a guidewire to be advanced past the targeted lesion. Afterwards, the apparatus will have the needed characteristics to provide support for advancement of coaxial catheters such as balloon catheters and stent delivery systems to the lesion site for treatment.
A further aspect of the invention is to provide such a guidewire with a filter, which securely retains thromboembolic fragments of the stenosis when the filter is retracted for removal from the blood vessel.
Another aspect of the invention is to provide such a guidewire with an extendable and retractable filter, minimizing trauma to the vessel as the guidewire is advanced and withdrawn to and past the lesion.
A further aspect of the invention is to achieve the foregoing aspects with minimum interruption of blood flow through the vessel.
These and other aspects of the present invention will be more apparent from the following description.